Soup herb is a term used to describe herbs that are commonly used in soups. The three most popular soup herbs are DILL, BASIL, and LEEK. DILL is a fragrant herb with a mild flavor that is often used in fish dishes. BASIL is a sweet-smelling herb with a slightly peppery taste that is often used in Italian dishes. LEEK is a mild onion-like vegetable with a subtle flavor that is often used in French dishes. All three of these herbs can be used to add flavor and depth to a variety of soups.